The present invention relates to an autostereoscopic reproduction system.
Compared with 2-dimensional, conventional representations, a 3-dimensional representation comes closer to natural visual perception. The degree of naturalness can be further enhanced by an autostereoscopic, position-adaptive representation. For this purpose, various autostereoscopic imaging methods have been developed which use either barrier masks, lenticular raster masks or prismatic raster masks for optical separation of right and left imaging directions for which different subpixel adaptations are required. Creating these representations required for 3-D animations, interactive games and vector-format films in real time on PCs has so far not been satisfactorily achievable, although stereoscopic films and projection techniques have been in use for years. These use, for instance, polarised light (horizontal/vertical or circular) in order to separate the left and right images. The technical advance of LCD technology made it possible to control the opacity of crystals electronically. This made possible the development of shutter technology whereby the right and left lens of a pair of spectacles alternately become opaque synchronously at half the image frequency and synchronously therewith, the right and left images appear sequentially on the image screen. This method is also used by autostereoscopic shutter monitors.
For several years, autostereoscopic reproduction systems with TFT displays have also been in use, which produce right and left images on an image screen horizontally multiplexed and create spatially separated projection directions by means of raster screens (DE-A-41 14 023, U.S. Pat. No. 6,307,585, DE-A-198 27 590, DE 198 22 342 and van Berkel in “Image for 3D-LCD, Philips Research Laboratories, UK, SPIE vol. 3639, 1999, pp. 84-91). Reproduction systems of this type can also be designed position-adaptive using head-trackers (U.S. Pat. No. 6,307,585 and Andiel, Hentschke et al. in “Eye-tracking for autostereoscopic displays using web cams”, SPIE vol. 4660, 2002, pp. 200-206).
In a known reproduction system of the aforementioned type (PAM, EP 0 836 332 A2), the individual image pixels of an image screen formed from three subpixels R, G and B are controlled by means of a coding unit line by line with right and left image strip signals such that in every line alternately right and left subpixel strips are formed, which serve to create image strips assigned to left and right, known in the following as horizontal “multiplexing” or “interlacing” of the left and right images. Furthermore, a raster screen in the form of a prismatic or lenticular raster screen is positioned in front of the image screen such that it brings together the right and left image strips for a defined viewing region in front of the image screen comprising, respectively, a right and a left viewing direction into the right and left images required for 3-D images. For reliable separation of the right and left images, those subpixels are set-dark which fall within empty regions or overlap regions, whereby empty regions contain subpixels not visible from both viewing directions and overlap regions contain subpixels visible from both viewing directions simultaneously. Furthermore, control of the subpixels visible only from the right viewing direction or only from the left viewing direction is performed such that each right or left subpixel strip has exactly three different-coloured subpixels side by side.
In this method of control, the sequence of the individual subpixels in the horizontal—or line—direction depends above all on the respective observer position that is notified to the coding unit, for instance, by means of an autostereoscopic position detector such as a head tracker or eye tracker. It could therefore occur that the sequence of subpixels in a selected subpixel strip is, for instance, RGB and in a subpixel strip lying adjacent to the left or right of it is, for instance, GBR or BRG. From this arises the as yet unsolved problem that colour faults may be thereby caused that at the borders of two subpixel strips, the same colours appear, for instance, if a subpixel strip BRG follows a subpixel strip RGB.